The present invention relates generally to transferring materials for well operations, and more particularly, to pneumatic particulate material fill systems and methods.
During the drilling and completion of oil and gas wells, various wellbore treating fluids are used for a number of purposes. For example, high viscosity gels are used to create fractures in oil and gas bearing formations to increase production. High viscosity and high density gels are also used to maintain positive hydrostatic pressure in the well while limiting flow of well fluids into earth formations during installation of completion equipment. High viscosity fluids are used to flow sand into wells during gravel packing operations. The high viscosity fluids are normally produced by mixing dry powder and/or granular materials and agents with water at the well site as they are needed for the particular treatment. Systems for metering and mixing the various materials are normally portable, e.g., skid- or truck-mounted, since they are needed for only short periods of time at a well site.
The powder or granular treating material is normally transported to a well site in a commercial or common carrier tank truck. Once the tank truck and mixing system are at the well site, the dry powder material must be transferred or conveyed from the tank truck into a supply tank for metering into a mixer as needed. The dry powder materials are usually transferred from the tank truck pneumatically. In the pneumatic conveying process, the air used for conveying must be vented from the storage tank and typically carries an undesirable amount of dust with it.
Cyclone separators are typically used to separate the dust from the vented air. However, cyclone separators which are small enough to be included with a portable mixing system have a limited capacity for storing solids separated from the air. When the dust collection container is filled, the collected dust may fill or clog the cyclone separator and dust is undesirably vented with what should be clean air or substantially clean air. To prevent undesirable dust discharge, the system must be stopped while the collection container is emptied.
Some fill system designs use a pressurized storage tank. In such systems, a pressurized air stream blows air and powder into the storage tank. The powder falls out of the pressurized air stream as the velocity drops with entry into the tank and while the air stream passes through a cyclone separator. The tank must be designed for pneumatic service with pressure relief and rupture elements to prevent overpressurization. Tanks commonly employ a metering feeder. While filling the tank during the operation of the metering feeder, the metering factor for the output of the feeder may change due to the vessel being pressurized. Thus, the accuracy and repeatability of the metering feeder is impacted by the pressurization.
Some fill system designs mount a cyclone separator and collection container above a storage tank to allow powder to fall from the separator to the tank. In such systems, the overall height of the assembly includes the height of the separator and collection container plus that of the storage tank. The height requirements of such designs are undesirable.
While embodiments of this disclosure have been depicted and described and are defined by reference to exemplary embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.